Scattering intensity of bicontinuous microemulsions and sponge phases

Peltomäki, Matti; Gompper, Gerhard; Kroll, D. M.

doi:10.1063/1.3701265

Cited by 28 publications

(33 citation statements)

References 59 publications

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“…Alternatively, membranes can be modeled as triangulated surfaces, 29,33,34 which require however discrete bond reconnections to describe topological changes. 33,35,36 After the first meshless-membrane model was proposed in 1991, 37 several meshless-membrane models have been developed. [30][31][32][38][39][40][41] In contrast to other meshless-membrane approaches, our models [30][31][32] are capable of separately controlling the membrane bending rigidity κ and the line tension Γ of membrane edges.…”

Section: Introductionmentioning

confidence: 99%

Structure formation of surfactant membranes under shear flow

Shiba

Noguchi

Gompper

2013

The Journal of Chemical Physics

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Shear-flow-induced structure formation in surfactant-water mixtures is investigated numerically using a meshless-membrane model in combination with a particle-based hydrodynamics simulation approach for the solvent. At low shear rates, uni-lamellar vesicles and planar lamellae structures are formed at small and large membrane volume fractions, respectively. At high shear rates, lamellar states exhibit an undulation instability, leading to rolled or cylindrical membrane shapes oriented in the flow direction. The spatial symmetry and structure factor of this rolled state agree with those of intermediate states during lamellar-to-onion transition measured by time-resolved scatting experiments. Structural evolution in time exhibits a moderate dependence on the initial condition.

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Section: Introductionmentioning

confidence: 99%

Structure formation of surfactant membranes under shear flow

Shiba

Noguchi

Gompper

2013

The Journal of Chemical Physics

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“…The basic assumption (eqn (3)) that k R,SANS is a linear combination of k 0 and k 0 is inferred from ref. 17 as the simplest ansatz consistent with the simulations. The combination of phase diagram measurements together with SANS-and NSE-experiments provided the necessary information to separate the different contributions and to determine the parameters a 1 and a 2 experimentally.…”

Section: Discussionmentioning

confidence: 76%

“…The simplest ansatz, as used in ref. 17, assumes that the bending rigidity measured by SANS is a linear combination of the two with prefactors a 1 and a 2 . One can then write for k 0,SANS :…”

Section: Introductionmentioning

confidence: 99%

Experimental determination of bending rigidity and saddle splay modulus in bicontinuous microemulsions

et al. 2013

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Elastic properties of surfactant membranes can be described in terms of the bending rigidity k and the saddle splay modulus k. Phase diagram measurements and neutron scattering experiments allowed the determination of these parameters. Recent simulations showed that the bending rigidity, which is deduced from the characteristic length scales in the microemulsion, is a mixture of k and k. By combining neutron spin echo (NSE) spectroscopy, small angle neutron scattering (SANS) and phase diagram measurements, we show that also experimentally the different contributions can be separated.For supercritical CO 2 microemulsions and bicontinuous microemulsions with additives, the prefactors of the k and k contributions are determined and compared to those from simulations.

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“…In this case, random surface models come into play that are based on Landau theory. 42,43 Here, we use the phenomenological model proposed by Teubner and Strey in which Gaussian fluctuations of the order parameter field determine the scattering intensity in the vicinity of the peak 34 to estimate the domain size and the correlation length of the structures formed at c s ≥ 0.46. The fits reveal a domain size d of 7.1 nm and 6.4 nm for c s = 0.46 and 0.56, respectively, and a correlation length ≤4.5 nm for both systems.…”

Section: Tubular Reverse Micelles and Interconnected Networkmentioning

confidence: 99%

Structure and dynamics of water in nanoscopic spheres and tubes

Loop

Ottosson

Lotze

et al. 2014

The Journal of Chemical Physics

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General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. We study the reorientation dynamics of liquid water confined in nanometer-sized reverse micelles of spherical and cylindrical shape. The size and shape of the micelles are characterized in detail using small-angle x-ray scattering, and the reorientation dynamics of the water within the micelles is investigated using GHz dielectric relaxation spectroscopy and polarization-resolved infrared pump-probe spectroscopy on the OD-stretch mode of dilute HDO:H 2 O mixtures. We find that the GHz dielectric response of both the spherical and cylindrical reverse micelles can be well described as a sum of contributions from the surfactant, the water at the inner surface of the reversed micelles, and the water in the core of the micelles. The Debye relaxation time of the core water increases from the bulk value τ H 2 O of 8.2 ± 0.1 ps for the largest reverse micelles with a radius of 3.2 nm to 16.0 ± 0.4 ps for the smallest micelles with a radius of 0.7 nm. For the nano-spheres the dielectric response of the water is approximately ∼6 times smaller than expected from the water volume fraction and the bulk dielectric relaxation of water. We find that the dielectric response of nano-spheres is more attenuated than that of nano-tubes of identical composition (water-surfactant ratio), whereas the reorientation dynamics of the water hydroxyl groups is identical for the two geometries. We attribute the attenuation of the dielectric response compared to bulk water to a local anti-parallel ordering of the molecular dipole moments. The difference in attenuation between nano-spheres and nano-cylinders indicates that the anti-parallel ordering of the water dipoles is more pronounced upon spherical than upon cylindrical nanoconfinement.

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Scattering intensity of bicontinuous microemulsions and sponge phases

Cited by 28 publications

References 59 publications

Structure formation of surfactant membranes under shear flow

Structure formation of surfactant membranes under shear flow

Experimental determination of bending rigidity and saddle splay modulus in bicontinuous microemulsions

Structure and dynamics of water in nanoscopic spheres and tubes

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